JPH0815161A - Chemiluminescence analyzer - Google Patents

Abstract

PURPOSE:To obtain a chemiluminescence analyzer which can perform highly accurate measurement while suppressing the effect of wet gas by stabilizing the potential in the vicinity of a photodiode to a constant level. CONSTITUTION:An optical window 8 is provided on one side of a reaction tank 9 fed with a sample gas and a reaction gas and a photodiode 11 detecting chemiluminescence, produced through reaction of both gases, is disposed oppositely to the optical window 8. In such a chemiluminescence analyzer, the optical window 8 is provided with conductivity and the potential thereof is dropped down to the earth potential.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemiluminescence analyzer for detecting the amount of chemiluminescence generated when a sample gas is reacted with a reaction gas and measuring the concentration of the sample gas based on the detection signal.

[0002]

2. Description of the Related Art FIG. 4 shows a main part of a conventional chemiluminescence analyzer. In this figure, 41 is a casing, into which a sample gas and a reaction gas are supplied, and one side of which is provided. Is provided with a reaction tank 43 having an optical window 42 for transmitting chemiluminescence generated by the reaction of both gases,
A photodiode 44 as a photodetector is provided so as to face the optical window 42. Reference numeral 45 is an electronic cooler for cooling the photodiode 44.

In the above chemiluminescence analyzer, for example, when NO gas is introduced as a sample gas and ozone is introduced as a reaction gas, these gases react in the reaction tank 43 to generate chemiluminescence, which is the photodiode 44.
The NO gas concentration can be detected based on the emission intensity.

[0004]

The sample gas introduced into the reaction chamber 43 of the chemiluminescence analyzer is not necessarily a dry gas, but a wet gas such as wet zero gas is also introduced. There is. When such a wet gas is introduced into the reaction tank 43, an electric charge (OH group) is generated on the surface of the optical window 42 on the inner side of the reaction tank due to water contained in the wet gas.
The potential of the optical window 42 fluctuates, and with this fluctuation of the potential, the potential of the room 46 in which the photodiode 44 is provided fluctuates, and the photodiode 44 using a semiconductor is adversely affected. As a result, a signal corresponding to the influence of moisture interference by the wet gas was generated in the output of the chemiluminescence analyzer.

The present invention has been made in consideration of the above matters, and stabilizes the potential in the vicinity of the photodiode to a constant potential, thereby reducing the influence of the wet gas and performing highly accurate measurement. It is an object of the present invention to provide a chemiluminescence analyzer capable of performing the above.

[0006]

In order to achieve the above object, the present invention provides an optical window on one side of a reaction tank to which a sample gas and a reaction gas are supplied, and at a position facing the optical window, In a chemiluminescence analyzer in which a photodiode for detecting chemiluminescence generated by the reaction of the two gases is arranged, the optical window is made conductive, and the optical window is dropped to the ground potential.

[0007]

In the chemiluminescence analyzer having the above structure, since the potential of the optical window of the reaction tank is lowered to the ground potential, the potential of the optical window is stabilized and the potential around the photodiode facing this optical window is reduced. It has been stabilized and the influence of moisture interference due to wet gas has been greatly reduced.

[0008]

1 and 2 are views showing an example of a chemiluminescence analyzer according to the present invention. In FIG. 1, reference numeral 1 denotes a casing having an upper opening, which is made of aluminum or the like. Two
Is a block-shaped container made of, for example, a fluororesin provided in the upper space of the casing 1 and having a circular shape in plan view. There is. Reference numeral 4 denotes a confluence portion which is communicated with the end portion of the spiral concave groove 3 on the center side and is provided on the bottom surface side in the shape of a bottomed hole. Reference numerals 5 and 6 communicate with opposite side surfaces of the confluence portion 4 and extend independently of each other on the upper flat surface side of the body 2, and 7 communicates with the outer peripheral side end portion of the spiral groove 3. This is the gas outlet path that is extended to the upper flat surface side of the container body 2.

Reference numeral 8 denotes an optical window which also serves as an optical filter and is in close contact with the side surface of the body 2 in which the spiral concave groove 3 is provided. The bath 9 is formed. The optical window 8 may be brought into close contact with the body 2 by pressing them or adhering them with an adhesive. In addition, 10 is an adhesive for bonding the optical window 8 to the inner surface of the casing 1.

Reference numeral 11 denotes a photodiode which is arranged in the lower space 12 of the body 2 so as to correspond to the optical window 8 in order to receive a light beam transmitted through the optical window 8. Reference numeral 13 denotes the temperature of the photodiode 11. In order to prevent the rise, it is an electronic cooler which is arranged at the lower part of the Peltier element, for example. The electronic cooler 13 is fixed to the inner surface of the bottom of the casing 1.

Reference numeral 14 designates a lid provided also on the upper portion of the body 2 and also serving as a flow passage board, and is made of, for example, stainless steel, and the lower surface of the lid is connected to the gas introduction passages 5 and 6 and the gas discharge passage 7, respectively. 15, 16 and 17 are opened, and the upper ends of these flow paths 15, 16 and 17 are formed to gas inlets 18 and 19 and gas outlet 20, respectively. In addition, 21, 22, 23, and 24 are the container 2 and the lid 14.
It is a sealing member such as an O-ring that is interposed between and.

In this embodiment, as shown in an enlarged view in FIG. 2, the lower surface of the optical window 8 is coated with an appropriate conductive paint [eg, transparent conductive film (ITO)] 25. A hole 27 in which the optical window 8 is made conductive and a metal spring 26 is opened in the casing 1
The inside of the spring 26 is inserted through the fixing member 28 such as a countersunk screw.
Is brought into pressure contact with the coating layer 25 of the optical window 8 so that the optical window 8 has the same potential as the casing 1 and the optical window 8 is dropped to the ground potential. In addition, 2
Reference numeral 9 is a cylindrical guide member made of, for example, a fluororesin that covers the spring 26 so that the spring 26 does not bend.

In the chemiluminescence analyzer having the above structure, for example, NO gas is supplied as a sample gas through the gas inlet 18.
In addition, ozone is introduced into the container 2 as a reaction gas through the gas introduction port 19. N introduced into the body 2
The O gas and ozone flow into the confluence portion 4, are mixed, and then flow through the spiral reaction tank 9 and flow out of the vessel body 2 through the gas outlet 20. Then, since the NO gas and ozone are mixed with each other in the confluence portion 4 and react with each other, the chemiluminescence generated while flowing through the reaction tank 9 is transmitted through the optical window 8 and is incident on the photodiode 11. The diode 11 detects and outputs a signal.

In the chemiluminescence analyzer having the above structure, the optical window 8 of the reaction tank 9 is lowered to the ground potential, so that the potential of the optical window 8 is stabilized. Further, since the photodiode 11 is held by the electronic cooler 13 fixed to the casing 1, the potential of the space 12 surrounded by the casing 1 and the optical window 8 is stabilized, so that the reaction tank 9 is wet. Even if gas is introduced, the potentials of the optical window 8 and the photodiode 11 are stabilized without fluctuation. That is, since the fluctuation of the potential around the photodiode 11 is eliminated, the influence of moisture interference by the wet gas is significantly reduced (about 30%).

Further, in the above embodiment, the optical window 8
Since only the spring 26 and the countersunk screw 28 are used to reduce the voltage to the ground potential, there is an advantage that the chemiluminescence analyzer can be easily assembled.

In the above embodiment, the spring 26 and the countersunk screw 28 are used to drop the optical window 8 to the ground potential, but instead of this, as shown in FIG. 3, the casing of the optical window 8 is used. The conductive adhesive 30 may be used for fixing to 1.

Further, in any of the above embodiments,
In order to make the optical window 8 conductive, a coating layer 25 made of a conductive paint was formed on one surface of the optical window 8. Instead of this, the optical window 8 itself is made of conductive glass. May be.

[0018]

As described above, according to the present invention, the optical window is made conductive, and the optical window is grounded to stabilize the potential of the optical window. The potential around the photodiode facing the window is stabilized, the influence of water interference by the wet gas can be significantly reduced, and the accuracy of the chemiluminescence analyzer can be improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a chemiluminescence analyzer of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a partially enlarged cross-sectional view of another embodiment.

FIG. 4 is a diagram for explaining a conventional example.

[Explanation of symbols]

 8 ... Optical window, 9 ... Reaction tank, 11 ... Photodiode.

Claims (1)

[Claims] 1. An optical window is provided on one side of a reaction tank to which a sample gas and a reaction gas are supplied, and a photodiode for detecting chemiluminescence generated by the reaction of the both gases is provided at a position facing the optical window. The arranged chemiluminescence analyzer is characterized in that the optical window is made conductive and the optical window is dropped to the ground potential.